The Assumption That Undid the World
by membridget
Summary: Everyone knows that the Potters had a son. After all, James and Lily always called their child 'Harry'. But did they really? With an abusive Uncle who'd do anything to hurt the Boy-Who-Lived, is it really a surprise that he'd run away and hide? But then why did Petunia join him? Dumbles-bashing, rated for references to abuse. HP/?


**Hey, I know I haven't written on any of my FT fanfics, and I am soo sorry. Unfortunately, my muse has moved onto HP. I will try to finish them, but just consider them on Hiatus for now. I do not own HP, however much I wish I did.**

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Chapter One:

Rosaline Harrietta Potter studied herself in the cracked mirror that sat on her wall in her tiny bedroom. For once, her long raven curls were loose, falling to mid-back. Her petite form was un-glamored, allowing all her scars to show. Thick, ragged scars marred her back where her Uncle had whipped her as a child. Across the small of her back was a jagged scar that just barely spelled out "freak". She ran her hands down her naked form, feeling the bumps of her scars. Her unhindered emerald eyes peered out from under her bangs, interrupted only by a thin lightning scar that stretched from her forehead to her jaw. The fifteen year old sighed, turning away to dress. She carefully wrapped her voluptuous chest until it was as flat as she could make it. Some padding was added to her waist, to straighten out her curves. Over that, she pulled a loose tank top and a large sweater, completely hiding her body. Dudley's old jeans from middle school did an excellent job of concealing her shapely legs. The teen glanced over herself one last time before focusing on her glamor. The glamor shimmered into being, hiding the various scars and shrinking the famous lightning scar.

"Rosie! Time to go!" Aunt Petunia's shrill voice broke through her daze. She slid on the thick glasses her Aunt had given her and grabbed her trunk, dragging it down the stairs. Aunt Petunia was finally taking her away from Number Four. She'd had enough of Vernon's abuse and feared what he might do if Rosaline were discovered. They were leaving while he was still at work. Rosaline had investigated her vaults in Gringotts and found that she owned many houses. So, she and her Aunt were going to Potter Manor. In Gringotts, Rosaline had also discovered the loophole from the wretched Tournament that allowed her to claim her Ladyship of the Potter family and be declared as an adult, allowing her to practice magic during the summer. Doing so, she had found that Dumbledore had been siphoning off small percentages of her money and paying for some organization called the Order of the Phoenix with her money. Of course, she had immediately stopped it, but Dumbledore wouldn't know for a little bit, thanks to the Gringotts goblins.

Her Aunt smiled at her tightly and led her to the car that she had managed to get Vernon to buy, "just in case Dudley needs to go to London". Rosaline loaded her trunk into the back of the car and climbed in. Petunia hit the gas and they were gone from Privet Drive.

Rose studied her Aunt as she drove. The woman had received a black eye from Vernon, as well as several nasty bruises along her arms. Rose wasn't much better herself. Her lip had been split and she had a few cuts from falling on broken glass. Finished with her perusal, she turned her gaze to the world passing by outside. They drove to London, leaving the car with a rather nasty note in front of Grunnings. Rose led Petunia to Diagon Alley, as it had been years since the woman had been there. They walked to Gringotts, where a portkey was waiting to take them to Potter Manor.

The Manor was enormous. And it was heavily warded. The ten house elves that lived there had been ecstatic to have a Mistress. Petunia had initially freaked out over them, but quickly grew fond of their hyper ways. Leaving Petunia to pick a room, Rosaline slowly wandered the Manor, stopping to chat with the portraits of her ancestors every so often. She'd found her grandparents and a younger portrait of her father in his teens. After tiring herself, she retired to the Master bedroom and removed all her disguises. She flopped onto the soft bed and fell asleep instantly.

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Meanwhile, the Order of the Phoenix was in a panic. Harry Potter was missing and Mundungus Fletcher had been absent whenever the boy had left. Sirius Black had just laughed when they told him his godson was missing from Privet Drive. They assumed Azkaban was still affecting his brain, but he was actually amused by his goddaughter. He'd thought someone would've figured it out, but hearing "Harry Potter" was missing had set him off. Of course, he also had a letter from his lovely Rose, explaining that she and Petunia were moving into her ancestral home, which he rightly assumed to be Potter Manor. He resolved to floo over for a visit as soon as his guests calmed down. The only other ones not panicking were Severus Snape and Remus Lupin. Snape, because he thought it was ridiculous to freak out because Potter had been missing for only two hours and Lupin, because Sirius had told him what was going on. Moony had settled next to Padfoot to watch the drama and laugh.

Severus had realized that Black knew what was going on and had relaxed, even though his first reaction had been panic. After all, it was Lily's son that was missing. But if the mutt wasn't worried, then the boy must have had a plan and had owled Black to inform him. He watched from the shadows as the Weasley's panicked, with Dumbledore yelling at Ronald for information. Unfortunately, it seemed his information block had been too effective, and Harry seemed to have stopped writing after the first letter that failed to give information.

Dumbledore was furious. The boy was supposed to be depressed, not planning an escape. He needed Harry to be downtrodden by his hideous uncle so that he would trust him. He was angry that his brilliant plan to keep the boy uninformed had backfired, and he was irritated that Black and Lupin were refusing to tell him where the boy had gone. The boy shouldn't have had anywhere to go either, so he assumed that the goblins were helping him. He resolved to vote positively on the next bill to restrict their rights. He swept away from Ronald, who was useless and unfortunately, loyal. The old wizard left Grimmauld Place in a huff, off to interrogate the goblins.

A twinkle entered Black's blue eyes once the Weasley's had gone back to their rooms and Albus was gone. "Care to visit our darling runaway?" he asked Moony, seemingly forgetting the presence of one Potions Master. He strode over to the fireplace and called out, "Potter Manor!", disappearing in a flash of green. Lupin shrugged his shoulders at Snape and followed his fellow Marauder. Snape rolled his eyes and followed the two men, promising himself that he was not acting like a foolhardy Gryffindor and was being a cunning Slytherin gathering information.

The entry hall at Potter Manor was enormous. The three men glanced around them, noting the lack of dust that meant someone had come home. Padfoot was off in an instant, transforming and following Rose's scent. After a couple of turnarounds, obviously the child had been exploring, Sirius seemed to have found the freshest scent. The other two followed the hyper dog to the Master bedroom, where he changed back. Sirius knocked on the door.

"Just a moment, Aunt Petunia," called out a very feminine voice. The door cracked open to reveal a buxom female draped in a dressing gown. Her eyes sprang open at the sight of her godfathers and she jumped on them with a squeal. "Sirius! Moony! I knew you'd get my letter!"

While the three became reacquainted, Severus had to remake the image of Harry Potter in his head, a Harry Potter who was most definitely female. He cleared his throat, making the three jump apart. The girl stared at him for a second before blushing and pulling the dressing gown around her tighter, unfortunately serving to only emphasize her assets. Severus stubbornly told himself that it was not a stirring he felt in his stomach, he was just hungry for something.

"Hello, Professor," she said shyly. Severus rolled his eyes.

"Does Poppy know?" he asked. The girl shook her head and Snape sighed.

Before he could ask anymore questions, Petunia Dursley found them. She glared harshly at the men, whose eyes instantly traced the black eye and bruises on her arms. She turned to her niece.

"Rosie, go get dressed. I'll entertain them."

Rose nodded and closed the door. The thumps from behind told them that she was obeying her aunt. Petunia led them away from the bedroom to one of the formal sitting rooms. She snapped her fingers and asked one of the elves for tea, looking very much at home in the stately manor. Severus settled into the corner of the room while the Marauders fell upon the tea like starving men.

The conversation was kept light, and far away from the lingering bruises on both Petunia and Rose. Sirius updated Petunia on the status of the Order and other friends she apparently knew through Lily. She had not known what had happened to the Longbottoms, though she had wondered why she was given custody over them. Remus shared short stories from school about Rose's adventures, which she had been unable or unwilling to tell her aunt before.

The girl in question entered the room wearing a pretty blue summer dress that emphasized her bust and fell freely just under it. Severus' mouth felt dry, so he grabbed a cup of tea to fix it. Meanwhile, Sirius and Remus studied the young girl. She looked tired, with bruises and cuts all over her face and arms. Scars that they knew had not been visible on Harry Potter were very visible on Rosaline Potter. When she leaned over to get her own cup of tea, the thick scars left from Vernon's whipping peeked out from under the dress.

"So how, Ms. Potter, did you manage to hide your gender from Madame Pomfrey?" Snape drawled, ignoring the scars he could see. It would not do to draw attention to them, Merlin knows he had hated that himself.

The girl blushed. "Well, she never did a full body exam. I used bindings and padding to give myself the general shape and a glamor covered the rest. Even with the Horntail, I was wearing a tank top, so I never had to take my shirt off."

"And why does the Wizarding World think you are 'Harry James Potter'?"

Rose laughed and gestured for Sirius to explain.

"Well, Rosie was named Rosaline Harrietta Potter, so James and Lily liked to call her Harry. I think I was the only other one present at the birth, so I was the only one who knew Rosie's gender. Everyone just assumed they'd had a son and thought his middle name would be his father's name. Even Moony thought so."

The werewolf blushed. "It's not my fault. Rosaline was born just before they went into hiding and James only ever called her 'Harry'. Besides, Lily kept dressing her up in neutral colors. What was I supposed to think?"

"Does Dumbledore know?" Severus asked. Rose shook her head, smiling.

"He insists on calling me his 'dear boy', and has never once asked me anything that would have to do with hiding my gender."

Severus nodded thoughtfully, still eying the teenager. Rose turned away and started an energetic conversation with her godfathers. He kept one ear open while he thought. Clearly, Dumbledore didn't know, or he'd have pressed it to his advantage to try and control Rose. Petunia watched Snape carefully, knowing that this man had caused a lot of grief in her life, not only is his part in her sister's death, but also in his bullying of her niece.

The two Marauders suddenly stood and made their excuses. Snape followed silently. They needed to get back before the Weasley's got concerned. The men floo-ed back to Grimmauld Place. Rose smiled gently at her aunt after they left and crawled onto the couch, patting the seat next to her.

Petunia accepted the invitation and pulled her niece into a loving hug. She placed a kiss on Rose's forehead. The two women sat in comfortable silence for the rest of the night.

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 **Hey folks. Review if you enjoyed! So I'm considering an HP/SS pairing for this story. Other possibilities include Rose x Ron, or Rose x Tom Riddle. Do let me know which you prefer. If you have another favorite you want, go ahead, but I will not be writing fem on fem, just because I have not idea how that would work, and please don't try and tell me in the comments. I know the physical, but as a heterosexual woman, it's a little hard to put myself in that mindset.**

 **Thanks for reading, Chapter two will be up as soon as I finish it!**

 **membridget**


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